Groin/hip discomfort

Hello, during my 20 mile long run last week I felt like I tweaked something in my hamstring area about half through but it wasn’t too noticeable so I powered through the rest of the run. This weekend i started to feel a dull achy consistent feeling in my groin/hip area right where the fold is under my pelvic region. It’s the most annoying when I sit down for long periods of time which is difficult not to do while I’m working. I haven’t run in 3 days to try to let this heal on it’s own but seems this dull achy pain has not subsided at all. I’m running NY in a few weeks so if have to rest until then I will. I don’t have much pain when I run but after a few miles I feel the area start to tighten up which worries me. I’m afraid to stretch the area as I don’t want to strain the muscles more but was looking for some possible advice if anyone else is dealing with something similar.